Diagnostic accuracy of PET for recurrent glioma diagnosis: a meta-analysis

Abstract

Background and purpose: Studies have assessed PET by using various tracers to diagnose disease recurrence in patients with previously treated glioma; however, the accuracy of these methods, particularly compared with alternative imaging modalities, remains unclear. We conducted a meta-analysis to quantitatively synthesize the diagnostic accuracy of PET and compare it with alternative imaging modalities.

Materials and methods: We searched PubMed and Scopus (until June 2011), bibliographies, and review articles. Two reviewers extracted study characteristics, validity items, and quantitative data on diagnostic accuracy. We performed meta-analysis when ≥5 studies were available.

Results: Twenty-six studies were eligible. Studies were heterogeneous in treatment strategies and diagnostic criteria of PET; recurrence was typically suspected by CT or MR imaging. The diagnostic accuracies of (18)F-FDG (n = 16) and (11)C-MET PET (n = 7) were heterogeneous across studies. (18)F-FDG PET had a summary sensitivity of 0.77 (95% CI, 0.66-0.85) and specificity of 0.78 (95% CI, 0.54-0.91) for any glioma histology; (11)C-methionine PET had a summary sensitivity of 0.70 (95% CI, 0.50-0.84) and specificity of 0.93 (95% CI, 0.44-1.0) for high-grade glioma. These estimates were stable in subgroup and sensitivity analyses. Data were limited on (18)F-FET (n = 4), (18)F-FLT (n = 2), and (18)F-boronophenylalanine (n = 1). Few studies performed direct comparisons between different PET tracers or between PET and other imaging modalities.

Conclusions: (18)F-FDG and (11)C-MET PET appear to have moderately good accuracy as add-on tests for diagnosing recurrent glioma suspected by CT or MR imaging. Studies comparing alternative tracers or PET versus other imaging modalities are scarce. Prospective studies performing head-to-head comparisons between alternative imaging modalities are needed.

Fig 1.

Study flow diagram.

Fig 2.

Receiver operator characteristic curves of PET for differentiating recurrent glioma from treatment-induced necrosis (¹⁸F-fluorodeoxyglucose PET for both high- and low-grade glioma histology [A], and high-grade glioma only [B], and ¹¹C-methionine PET for high-grade glioma only [C]). The size of each circle is proportional to the sample size of the corresponding study (all study participants). The dashed line represents the 95% confidence region for the summary sensitivity and specificity (depicted by a square).